172 
Journal of Agricultural Research 
Vol. XI, No. 4 
bring about fasciation in plants, but in the case of such varieties of 
peas as the Mummy (Pi), the cause is innate or hereditary. 
The expression of (Gc) (12) changes to a deeper brown, resembling that 
of (Gc) (12) and J (17) combined, if the ripe seeds remain exposed to the 
weather or even ripen under conditions of much alternation of sun and 
rain. Under greenhouse conditions water rarely touches the ripe seeds. 
The expression of factor G (13) fades on prolonged exposure to sunlight 
and wet weather, and seeds of wrinkled-seeded varieties fade more 
quickly than those of green round-seeded forms. Tack of sufficient 
sunlight, immaturity due to prolonged growth of the vine, and other 
environmental factors effect the action of factor I (16) on green coty¬ 
ledon pigment, especially in such varieties as Spate Gold (P29). Pitting 
or “spurious indent” resembling the expression of factors h x (18) and 
l 2 (19) is found as an environmental effect in peas from which these 
factors are absent. This is commonly the case in field-grown seeds in 
this locality of such white-flowered, ^ round-seeded varieties as Tall 
Acacia (P39), First of All (P22), and Black-Eyed Marrowfat (P14). 
Factor (Le) (20) is generally responsible for the difference between 
dwarf and tall peas, and this difference may be noted as soon as the 
plants are 2 to 3 weeks old. Factor T (31), aside from the fluctuations 
caused by differences in environment, is responsible for the number of 
internodes. Pea varieties may be classified into three general types as 
regards height—dwarfs, half dwarfs, and tails. Dwarfs have 8 to 15 
short intemodes. Half dwarfs are at least of two general types—plants 
with 10 to 18 long intemodes or 20 to 30 short ones. Tall peas are 
made up of a large number of long intemodes (35 to 60). Other heredi¬ 
tary elements not yet isolated, together with environmental conditions 
such as disease, very poor soil, and dry, hot weather, modify the expres¬ 
sion of these factors, especially T (31). The absence of factor (Fa) (10), 
bringing about fasciation, modifies height by shortening the inter¬ 
nodes, though possibly the number of intemodes is increased. Factor 
M (22) expresses itself very faintly (“ghost mottling”) in the absence of 
factor A (1) for flower color. Prolonged exposure to sun and rain after 
the seeds are mature darkens the brown pigment. 
The expression of factor O (24) may be modified or almost entirely 
suppressed by certain diseases or the lack of sufficient salts, such as 
potassium. Sickly yellow foliage results, somewhat resembling varieties 
from which O is absent, though whiter and duller. Crosses involving 
factors G, O, and R (13, 24, 29) apparently give complex results. 
Either the presence of the shape factor R (29) causes no zygotes to be 
formed in which R is present and G and O are absent, or the presence of 
R in some way brings about the production of green pigment, even 
though G (13) is absent. More data are being accumulated, and it is 
hoped these particular problems will be solved shortly through their aid. 
The expression of factor S (30), in the absence of which pea seeds are 
